Vehicles such as boats and motor homes are usually provided with several different types of consumers of electrical energy, such as lamps, refrigerators, bilge pumps, navigation equipment, cooking equipment and other types of electrical equipment. A re-chargeable lead-acid service battery is often provided to supply the different consumers with electrical energy. In order to ensure proper operation of all the electrical equipment in the vehicle the battery should be charged regularly. Charging arrangements can be provided so that when the engine of the vehicle is running the battery is charged.
There are many aspects to consider in order to prolong the service life and retain the performance of the battery. The battery may remain idle for long periods e.g. during the winter time in the case of a boat. During the summer time the battery may instead be put under a lot of strain by the electrical equipment installed in the vehicle and may be used very frequently without the engine being turned on. This is naturally very taxing for the battery.
In the 1990s, battery charging underwent a robust period of development, which introduced a new type of maintenance and care, wherein focus was put on efficient charging the battery in such a way that the service life of the battery was prolonged and such that the battery could provide the maximum performance for all of this time. Multi-stage charging as disclosed in the U.S. Pat. No. 7,541,778 provides such efficient battery charging.
Nowadays people have come to rely on everything working properly to ensure that they have the time to do everything they have planned. Therefore, people's expectations and requirements on all the vehicles around them have increased. Correct battery care can avert many disappointments and problems. People also have different expectations and requirements on different types of electrical equipment in the vehicle. While it may be somewhat annoying if the refrigerator is not working in the boat, a bilge pump unable to operate may lead to a really hazardous situation.
There's a built-in conflict between battery charge and load use voltage. The charge voltage for a battery depends on the temperature and should normally be at about 14.4V at 25 degrees C. A cold battery should with preference be charged at a higher voltage and a warm at a lower voltage. 12V consumers like light bulbs, electronics and LED light have significantly longer expected life if the voltage is lower. Typically the expected life of a light bulb is reduced by 50% if the voltage is increased 5%.
Consequently there are several different needs and requirements with respect to electrical energy consumption to consider in a vehicle. The battery has certain demands that need to be fulfilled in order to achieve efficient charging that differ from the demands of other electrical equipment. Furthermore there are different expectations and requirements on different types of electrical equipment as explained above. It is thus a challenging problem how to supply electrical energy to consumers and for charging the battery and at the same time fulfill differing demands and requirements.